/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/************************************************************************
 * libc/math/lib_sinf.c
 *
 * This file is a part of NuttX:
 *
 *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
 *   Ported by: Darcy Gong
 *
 * It derives from the Rhombs OS math library by Nick Johnson which has
 * a compatibile, MIT-style license:
 *
 * Copyright (C) 2009-2011 Nick Johnson <nickbjohnson4224 at gmail.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 ************************************************************************/

/************************************************************************
 * Included Files
 ************************************************************************/

#include <sys/types.h>
#include <math.h>

/************************************************************************
 * Private Data
 ************************************************************************/

static float _flt_inv_fact[] = {
	1.0 / 1.0,					/* 1 / 1! */
	1.0 / 6.0,					/* 1 / 3! */
	1.0 / 120.0,				/* 1 / 5! */
	1.0 / 5040.0,				/* 1 / 7! */
	1.0 / 362880.0,				/* 1 / 9! */
	1.0 / 39916800.0,			/* 1 / 11! */
};

/************************************************************************
 * Public Functions
 ************************************************************************/

float sinf(float x)
{
	float x_squared;
	float sin_x;
	size_t i;

	/* Move x to [-pi, pi) */

	x = fmodf(x, 2 * M_PI);
	if (x >= M_PI) {
		x -= 2 * M_PI;
	}

	if (x < -M_PI) {
		x += 2 * M_PI;
	}

	/* Move x to [-pi/2, pi/2) */

	if (x >= M_PI_2) {
		x = M_PI - x;
	}

	if (x < -M_PI_2) {
		x = -M_PI - x;
	}

	x_squared = x * x;
	sin_x = 0.0;

	/* Perform Taylor series approximation for sin(x) with six terms */

	for (i = 0; i < 6; i++) {
		if (i % 2 == 0) {
			sin_x += x * _flt_inv_fact[i];
		} else {
			sin_x -= x * _flt_inv_fact[i];
		}

		x *= x_squared;
	}

	return sin_x;
}
